Wireline equipment is frequently used to install and retrieve downhole devices within a wellbore. The equipment used to install these downhole devices within the wellbore are generally referred to as running tools. The equipment used to retrieve these downhole devices from a wellbore are generally referred to as pulling tools.
Many forms of running tools, pulling tools and combination running and pulling tools have been developed. Typically, these tools engage an external or internal fishing neck on the downhole devices to be run into or pulled from the wellbore on wireline. These tools are typically operated by either upward or downward jarring of the tool. For example, when running a downhole device, upward or downward jarring may be used to lock the device in place. Similarly, upward or downward jarring may be used to operate a downhole device that is previously installed within the wellbore. Upward or downward jarring is also used to engage the fishing neck of a downhole device installed within a wellbore and may be used to unlock the downhole device from the wellbore. Upward or downward jarring is also used to release from the fishing neck of a downhole device after the downhole device is locked in place. In addition, if a downhole device cannot be unlocked, upward or downward jarring may be used to release the running or pulling tool from the downhole device.
Specifically, running tools have been developed to engage the fishing neck of a lock mandrel having a flow control device, such as a plug. Once the running and pulling tool is lowered into the wellbore, upward or downward jarring may be used to install the lock mandrel and flow control device in the wellbore in order to prevent the flow of production fluids therethrough. When it is desired to continue production from the wellbore, the lock mandrel and flow control device must be removed. A pulling tool may then be run downhole to engage the lock mandrel using upward or downward jarring as required to unlock the lock mandrel and flow control device from the wellbore for retrieval.
It has been found, however, that in high pressure wells, the use of conventional pulling tools may result in the pulling tool along with the lock mandrel being blown uphole. Specifically, when the pulling tool engages the fishing neck of the lock mandrel, an equalization valve in the flow control device is typically opened. When the equalization valve is opened, high pressure fluid tends to force the pulling tool up through the wellbore. Since conventional pulling tools engage the fishing neck of the lock mandrel prior to opening the equalization valve, the high pressure fluid forces the pulling tool upward which may unlock the lock mandrel thereby causing the pulling tool, along with the lock mandrel, to be blown uphole. In addition, it has been found that the maximum upward jarring force that may be exerted by a conventional pulling tool on the lock mandrel once the fishing neck is properly engaged is limited by the shear force required to shear the release pin. If the release pin is inadvertently sheared, the pulling tool will release from the lock mandrel, leaving the lock mandrel and the flow control device downhole. If the flow control device has an equalization valve as described above, high pressure fluid may now blow uphole.
Therefore, a need has arisen for a pulling tool which may be used to pull a downhole device from a wellbore. A need has also arisen for such a pulling tool that will not be blown uphole along with the downhole device being retrieved during equalization. A need has further arisen for a pulling tool that may be upwardly jarred without being limited by the shear force that allows emergency release.